Independent Active and Reactive Power Control for Single Stage H8 Transformer-less Solar PV Inverter

With the rapid development in power electronics technologies and solar photovoltaic (PV) cells, the interest in solar PV cell-based electric power generation and other applications is increasing more incredibly. For low power grid or direct load applications, single-stage solar PV inverters without transformers are advantageous. Based on this concept solar single-stage eight switch H8 based transformerless solar PV inverter is proposed. The objective of the work is to present a control scheme for the H8 inverter to have better power handling capability and for independent active and reactive power control. For this, the test system is studied using MATLAB/ SIMULINK software under three cases (i) constant active power and varying reactive power, (ii) varying active power and constant reactive power, and (iii) varying both active and reactive power. The proposed inverter is compared with single-stage solar PV with two switches boost and six switches inverter topology. It is found that power flow ripples and surges are lesser for proposed H8 than with single-stage topology.

Voltage and Reactive Power Control in DFIG Wind Farm Load bus by FACT Device – UPFC

This paper deals with the analysis and simulation of the Unified Power Flow Controller (UPFC) for Grid connected DFIG wind farm system mitigation. The purpose of the paper is to derive and analyze a reactive power control strategy of UPFC dedicated for DFIG mitigation. The FACT device Unified Power Flow Controller (UPFC) is connected with load bus. Paper has demonstrated the improvement in voltages, power transferred to grid, active and reactive power control. Matlab/simulink is used for the work. Paper demonstrated the simulation results for with and without UPFC for Grid connected Doubly Fed Induction Generator wind farm system.

Reactive power control

The article investigates the methods of control of reactive power modes. It is shown that ensuring the efficiency of electricity transmission and distribution is inseparable from setting and solving problems related to reducing electricity losses in networks. Moreover, one of the most effective ways to reduce electricity losses, as well as improve its quality at the terminals of electrical receivers is to compensate for reactive power, which is carried out using various compensating devices. It is shown that the control of the reactive power mode is carried out in accordance with the Methodology for calculating the fee for the flow of reactive energy between the power transmission organization and its consumers. It is shown that the indicator of economically advantageous value of the level of reactive energy consumption can be cos φз, the value of which is predetermined. The procedure for controlling the reactive power mode contains two main stages: the stage of determining the magnitude of the possible reduction of the current cos φ above the set and the stage of determining and implementing control effects aimed at eliminating possible deviations. Preferably, it is preferable to focus on those methods that are based on the study of forecast estimates, which constitute the source information for management decisions. It is expedient to use adaptive methods of exponential smoothing as a basis for operative forecasting of electric loading. Reactive power mode is controlled by compensating units. It is shown that the control of voltage modes in the power supply system significantly affects the modes of reactive power consumption. In this regard, it is advisable to comprehensively solve the problem of reactive power control both by controlling the compensating units and the impact on the voltage regimes of the power supply system. In the calculation model, the reactive load of the distribution network is given by its static characteristics, which can be the basis for regulating the reactive load. To implement regulation in the power supply centers of electrical networks, technical means are provided on the basis of changing the transformation coefficient or generating reactive power by counter-voltage regulation.

Reactive power control of grid-connected photovoltaic micro-inverter based on third-harmonic injection

<span lang="EN-US">This paper presents four interleaved flyback DC-DC converters. Each flyback converter contains a separate maximum power point tracker (MPPT). The MPP tracker is used to collect the maximum power value from photovoltaic panel by using (P&amp;O) algorithm with an output of reference current. In latest years, the active third-harmonic injection circuit have received much interest, this technique contributed to getting a better quality of injection current into the utility grid and control the reactive power. For converting direct current to three-phase sinusoidal currents, a line-commutated current source inverter type (CSI) with filter is used. The developed micro-inverter of (1000 W) offers an expanded range of reactive power control with balanced three-phase output power and good efficiency 95.07%. The effectiveness of the suggested system is clarified through the MATLAB program simulation. The system proposed in this paper has proven its effectiveness in obtaining reactive power control, nearly sinusoidal three-phase output currents and it is compared with the traditional PV micro-inverter system. The comparison shows that the PV micro-inverter is best in more specification than the traditional PV system such as efficiency and total harmonic distortion (THD) and the system losses.</span>